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(#) Layout hierarchy is too deep

!!! WARNING: Layout hierarchy is too deep
   This is a warning.

Id
:   `TooDeepLayout`
Summary
:   Layout hierarchy is too deep
Severity
:   Warning
Category
:   Performance
Platform
:   Android
Vendor
:   Android Open Source Project
Feedback
:   https://issuetracker.google.com/issues/new?component=192708
Since
:   Initial
Affects
:   Resource files
Editing
:   This check runs on the fly in the IDE editor
Implementation
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/TooManyViewsDetector.java)
Tests
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/TooManyViewsDetectorTest.kt)
Copyright Year
:   2011

Layouts with too much nesting is bad for performance. Consider using a
flatter layout (such as `RelativeLayout` or `GridLayout`).The default
maximum depth is 10 but can be configured with the environment variable
`ANDROID_LINT_MAX_DEPTH`.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
res/layout/too_deep.xml:44:Warning: too_deep.xml has more than 10
levels, bad for performance [TooDeepLayout]
    &lt;LinearLayout
     ------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`res/layout/too_deep.xml`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers
&lt;LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"
    android:layout_height="match_parent"&gt;

    &lt;Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Ok" /&gt;

    &lt;LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"&gt;

        &lt;LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"&gt;

            &lt;LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"&gt;

                &lt;LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"&gt;

                    &lt;LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"&gt;

                        &lt;LinearLayout
                            android:layout_width="match_parent"
                            android:layout_height="match_parent"&gt;

                            &lt;LinearLayout
                                android:layout_width="match_parent"
                                android:layout_height="match_parent"&gt;

                                &lt;LinearLayout
                                    android:layout_width="match_parent"
                                    android:layout_height="match_parent"&gt;

                                    &lt;LinearLayout
                                        android:layout_width="match_parent"
                                        android:layout_height="match_parent"&gt;

                                        &lt;LinearLayout
                                            android:layout_width="match_parent"
                                            android:layout_height="match_parent"&gt;

                                            &lt;LinearLayout
                                                android:layout_width="match_parent"
                                                android:layout_height="match_parent"&gt;

                                                &lt;Button
                                                    android:layout_width="wrap_content"
                                                    android:layout_height="wrap_content"
                                                    android:text="Ok" /&gt;

                                            &lt;/LinearLayout&gt;
                                        &lt;/LinearLayout&gt;
                                    &lt;/LinearLayout&gt;
                                &lt;/LinearLayout&gt;
                            &lt;/LinearLayout&gt;
                        &lt;/LinearLayout&gt;
                    &lt;/LinearLayout&gt;
                &lt;/LinearLayout&gt;
            &lt;/LinearLayout&gt;
        &lt;/LinearLayout&gt;
    &lt;/LinearLayout&gt;
&lt;/LinearLayout&gt;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/TooManyViewsDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `TooManyViewsDetector.testTooDeep`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=192708.

(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Adding the suppression attribute `tools:ignore="TooDeepLayout"` on
  the problematic XML element (or one of its enclosing elements). You
  may also need to add the following namespace declaration on the root
  element in the XML file if it's not already there:
  `xmlns:tools="http://schemas.android.com/tools"`.

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="TooDeepLayout" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'TooDeepLayout'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore TooDeepLayout ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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